* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter Outline
Plant use of endophytic fungi in defense wikipedia , lookup
History of botany wikipedia , lookup
Plant breeding wikipedia , lookup
Plant stress measurement wikipedia , lookup
Plant defense against herbivory wikipedia , lookup
Photosynthesis wikipedia , lookup
Plant ecology wikipedia , lookup
Plant secondary metabolism wikipedia , lookup
Venus flytrap wikipedia , lookup
Plant nutrition wikipedia , lookup
Ornamental bulbous plant wikipedia , lookup
Plant physiology wikipedia , lookup
Plant reproduction wikipedia , lookup
Evolutionary history of plants wikipedia , lookup
Flowering plant wikipedia , lookup
Plant evolutionary developmental biology wikipedia , lookup
Plant morphology wikipedia , lookup
Chapter Outline I. Plants Fuel You (and Soon Your Car) A. Grasses are among the most successful plant groups, and they have long produced food crops for us such as corn, wheat, and rice. 1. Now, a particular grass called switchgrass could become the biofuel that will drive your car. 2. In the past, switchgrass was a significant part of the tall-grass prairie that covered much of the Midwest. a) Switchgrass is strong and tough, and can grow to be 30.80 cm high. b) Bioengineering is making switchgrass even hardier. c) Switchgrass can be harvested every year for at least ten years before replanting is needed. d) Switchgrass takes in more carbon dioxide while growing than it releases when it is burned, making it a good source of energy. B. A good source of biofuels: 1. Is renewable 2. Is not a food source for humans 3. Can grow on land that is not farmable 4. Will produce a new crop every year 5. Returns more energy than is needed to produce it 6. Takes in more carbon dioxide while growing that it gives off when burned C. The consensus is that switchgrass is an energy crop that can supply as much biofuel in one year as the 1970 peak oil production in the United States. II. Organs and Tissues of Flowering Plants _______ Critical concepts include: plant anatomy, organs, monocots, eudicots, differences of groups, uses of monocots, apical meristems, primary tissues (epidermal, ground, vascular), specialized cell types, and organization of tissues in the plant organs. 22.1 Flowering plants typically have roots, stems, and leaves A. The flowering plants, or angiosperms, are extremely diverse, yet share many structural features. 1. Most flowering plants have a shoot system and a root system. a) The shoot system consists of the stem, branches, leaves, and flowers. b) The root system consists of the main root and its branches. 2. The stem, leaf, and root are the three vegetative organs of plants. B. The Stem 1. A stem performs four main functions: a) Support of leaves and flowers b) Growth of the stem c) Transport of water and nutrients d) Sometimes food storage 2. A stem can grow because it has a terminal bud in the shoot tip. a) The activity of the terminal bud produces tissues that become new leaves and new axillary buds. b) The part of the stem where new leaves and axillary buds are found is called a node. c) An internode is the region between the nodes. 3. A stem not only supports the leaves so that they are better exposed to sunlight, but also contains the vascular tissue that brings water to them and takes away the products of photosynthesis. 4. Stems can store the products of photosynthesis. a) Some plants have a fleshy horizontal underground stem called a rhizome. 5. Stems can be highly modified. C. Leaves 1. Leaves are the chief organs of photosynthesis. 2. The wide portion of a foliage leaf that absorbs solar energy is called the blade. a) The blade is held away from the stem by a stalk called a petiole. 3. Leaves are adapted not only to carry on photosynthesis but also to environmental conditions. a) Some trees in the temperate zone are deciduous, meaning they lose their leaves only to have them grow back in the spring. D. Roots 1. Like shoot tips, root tips can grow their entire lives. 2. Roots have three main functions: a) Anchor the plant in the soil b) Absorb minerals and water from the soil c) Produce hormones 3. The higher surface-to-volume ratio of a root system is increased by the presence of root hairs, which are delicate extensions of mature root cells. 4. Roots produce hormones that ensure the root system will be a size appropriate to the needs of the shoot system. 5. The two main types of roots are taproots and fibrous roots. 22.2 Flowering plants are either monocots or eudicots A. Plants manage to grow from seeds before they have fully developed organs because seeds have cotyledons. 1. Plants with one cotyledon are known as monocotyledons, or monocots. a) Ex: grasses, tulips, daffodils 2. Plants with two cotyledons are known as Eudicotyledons, or eudicots. a) Ex: kidney beans, peas, lima beans 3. The cotyledons of eudicots supply nutrients while the cotyledons of monocots act largely as a transfer tissue for nutrients derived from the endosperm. 4. Eudicots used to be called dicots. B. There are structural differences between adult eudicots and monocots. 1. Vascular tissue in the root a) In monocots—vascular tissue occurs in a ring. b) In eudicots—xylem has a star shape while phloem is located between the arms of the xylem. 2. Vascular tissue in the stem a) In monocots—vascular bundles are scattered throughout the ground tissue. b) In eudicots—the vascular bundles occur in a ring. 3. Leaf veins a) In monocots—parallel venation b) In eudicots—netted venation 4. Flower a) In monocots—flower parts in threes or multiples of three b) In eudicots—flower parts in fours or fives or multiples 5. Pollen grains a) In monocots—one aperture b) In eudicots—three apertures C. The eudicots are the larger group and include some of our most familiar flowering plants. How Biology Impacts Our Lives 22A Monocots serve Humans Well A. The monocots have great importance. 1.The domestication of monocot plants included selective breeding. B. Corn is the most important crop plant in the United States. 1. Three of the world’s most populous nations are rice-based societies. C. Beer is also produced from cereal grain. 1. The specific grain to be fermented varies geographically among all the beer-producing cultures. D. Bamboo can grow up to a foot a day. 1. It can be consumed by humans as a vegetable. 2. It can be used for making musical instruments, furniture, etc. E. Most of the flowers bought and sold are monocots. 1. Floriculture is a multi-billion-dollar industry in the United States alone. 22.3 Plants have specialized cells and tissues A. Flowering plants grow in size their entire life because they have meristematic (embryonic) tissue composed of cells that divide. 1. Apical meristem is located in the terminal bud of the shoot system and in the root tip. 2. Each primary meristem produces a particular tissue type during the life of a plant. a) Epidermal tissue – contains flat epidermal cells. b) Ground tissue – contains large, thin-walled parenchyma cells. c) Vascular tissue - contains xylem and phloem. B. Epidermal tissue 1. The entire body of a plant is covered by a layer of closely packed epidermal cells called the epidermis. a) Cells exposed to air are covered with a waxy cuticle to minimize water loss. b) In leaves, the epidermis often contains stomata, small opening surrounded by guard cells. 2. In the trunk of a tree, the epidermis is replaced by periderm, which contains cork. a) Lenticels, which are breaks in the periderm, function in gas exchange. C. Ground tissue 1. Ground tissue forms the bulk of stems, leaves, and roots. 2. It is composed of three types of cells. a) Parenchyma cells—the least specialized b) Collenchyma cells—thick primary walls c) Sclerenchyma cells—thick secondary cell walls impregnated with lignin (most are nonliving at maturity) D. Vascular tissue 1. Xylem transports water and minerals from the roots to the leaves. a) Xylem contains conducting cells called vessel elements and tracheids. b) The end walls of vessel elements are arranged to form a vessel. 2. Phloem transports sugar and other organic compounds, usually from the leaves to the roots. a) The conducting cells are sieve-tube members, arranged to form a continuous sieve tube. b) Sieve-tube members, which have no nuclei, have companion cells with nuclei. 3. Vascular tissue extends from the root through the stem to the leaves and vice versa. 22.4 The three types of plant tissues are found in each organ A. In all three organs of a plant, the epidermal tissue forms the outer cover, and the vascular tissue is embedded within ground tissue. B. Leaf 1. The upper epidermis often bears protective hairs and/or glands that secrete irritating substances to provide some protection against predation. 2. The upper and lower epidermis has an outer, waxy cuticle, which prevents water loss but also prevents gas exchange. 3. Stomata are located in the lower epidermis. 4. The interior of a leaf is made of mesophyll, a ground tissue. a) There are two distinct regions: palisade mesophyll and spongy mesophyll. 5. Leaf veins branch and terminate in the mesophyll. C. Stem 1. Plants that have nonwoody stems are termed herbaceous plants. a) The ground tissue in the stem consists of the cortex and the central pith. b) Herbaceous stems have distinctive vascular bundles containing xylem and phloem. 2. The vascular tissue of a stem supports the shoot system so that the leaves can collect solar energy for photosynthesis. D. Root 1. The epidermis usually consists of only a single layer of rectangular cells that are thin-walled and able to absorb water and materials. a) At maturity, many epidermal cells have root hairs. 2. Large, thin-walled parenchyma cells make up the cortex. 3. The endodermis is a single layer of cells that fit snugly together and form the outer tissue of the vascular cylinder. a) A layer of impermeable suberin forces water and minerals to pass through endodermal cells. b) Just inside the endodermis layer is the pericycle, a layer of actively dividing cells from which lateral branch roots arise. III. Growth of Roots and Stems _________________________ Critical concepts include: primary growth in the shoot and root, zones, organization, secondary growth, lateral meristems, bark, cork, and wood. 22.5 Primary growth lengthens the root and shoot systems A. Primary growth, which causes a plant to grow lengthwise, is centered in the apex of the shoot and the root. 1. Meristem is a region of actively dividing cells. 2. The existence of meristematic tissue allows a plant to keep growing its entire life span. 3. Plant organs grow toward or away from stimuli. B. Root system 1. The growth of many roots is continuous, pausing only when conditions are poor. 2. The zone of cell division is protected by the root cap. a) The zone of cell division contains the root apical meristem. b) These meristematic cells give rise to the primary meristems, called protoderm, ground meristem, and procambium. 3. The zone of elongation is the region where the root increases in length. 4. The zone of maturation is the region that contains fully differentiated tissues. C. Shoot system 1. The terminal bud includes the shoot apical meristem and also leaf primordia (young leaves). 2. The shoot apical meristem produces everything in a shoot: leaves, axillary buds, additional stem, and sometimes flowers. a) It also gives rise to the same primary meristems as in the root. b) These develop into the differentiated tissues of a shoot system. c) Protoderm becomes the epidermis of the stem and leaves. d) Ground meristem becomes the cortex and pith in the stem and mesophyll in the leaves. e) Procambium differentiates into the xylem and phloem of a vascular bundle. f) Mature vascular bundles contain fully differentiated xylem, and phloem, and a lateral meristem called vascular cambium, which is responsible for secondary growth. D. Winter twig 1. The anatomy of a winter twig shows the changes that allow a stem to overwinter. 2. The terminal bud is protected by leaves modified to be small, dry, terminal bud scales. a) Leaf scars and vascular bundle scars mark the spot of abscission (dropoff). 3. You can tell the age of a stem by counting these terminal bud scale scars. 22.6 Secondary growth widens roots and stems A. Secondary growth occurs only in woody plants, where it increases the girth of trunks, stems, branches, and roots. 1. In a stem, primary tissues continue to form each year from primary meristems produced by the shoot apical meristem. 2. Secondary tissues occur due to the growth of lateral meristems: vascular cambium and cork cambium. B. Secondary growth begins because of a change in the activity of vascular cambium. 1. Vascular cambium divides parallel to the surface of the plant and produces secondary (new) xylem and phloem each year. C. A wood stem has three distinct areas: the bark, the wood, and the pith. 1. Wood is actually secondary xylem that builds up year after year. a) In spring wood, wide vessels transport sufficient water to the growing leaves. b) Summer wood contains a lower proportion of vessels and a higher number of tracheids. c) The annual ring is made up of the spring wood followed by summer wood for one year’s growth. 2. The bark of a tree contains periderm and phloem. a) The periderm is a secondary growth tissue that contains cork and cork cambium. b) Cork cambium lies beneath the epidermis, but later it is part of the periderm. c) Cork cambium divides and produces cork cells that give bark its characteristic appearance. d) The impermeable cork may be interrupted by lenticels, pockets of loosely arranged cork cells not impregnated with suberin. e) Secondary phloem does not build up as xylem does. 3. Xylem rays and phloem rays consist of parenchyma cells that permit lateral conduction of substances from the pith to the cortex and some storage of food. D. Advantages and disadvantages of being woody 1. Woody plants have enough xylem and phloem to satisfy needs. 2. Reduced competition. 3. Metabolically expensive. 4. Needs more defense mechanisms. How Life Changes 22B The First Forests A. Scientists pieced together the fossil remains of a woody tree that lived in the Devonian period. 1. They named the tree Eospermatopteris and hypothesized that it stood 900 m tall. 2. The tree looked much like a palm tree. B. Wood fossilizes well, and botanists have been able to determine how ancient wood evolved the vessel elements of today’s wood. 1. In ancient wood, xylem was composed of long cells with tapered ends, much like the tracheids of today’s wood. 2. Later the cells became shorter, and the tapered ends became flatter and developed perforated end walls. C. The trees of the first forests lowered the local temperature and removed vast quantities of carbon dioxide from the atmosphere when they photosynthesized. 1. They also altered local hydrologic cycles. 2. The result was the creation of habitats that enabled animals to invade the land environment. D. As soon as modern vascular tissue evolved, so did trees that could grow taller and wider. IV. Homeostatic Mechanisms of Plants ___________________ Critical concepts include: homeostasis, organization and anatomy of a leaf, symbiotic relationships, and defense mechanisms.. 22.7 Leaves are organized to carry on photosynthesis A. Leaves as Organs of Homeostasis 1. Plants, like other organisms, have an organization suited to main homeostasis. 2. The functions of a foliage leaf are to carry on photosynthesis, regulate water loss, and be protective against parasites and predators. 3. Epidermal tissue is located on the leaf’s upper and lower surfaces. a) Epidermis contains trichomes, little hairs that are highly protective, especially when they secrete irritating substances against predators. b) Epidermal cells play a significant role in regulating water loss. B. Leaves are the chief photosynthesizing organs of a plant. 1. Leaves must absorb solar energy, take up carbon dioxide, and receive water by way of leaf veins. a) Palisade mesophyll carries on most of the photosynthesis. b) Foliage leaves are generally flat and thin—this shape allows solar energy to penetrate the entire width of the leaf. 2. Leaf veins bring water and minerals to a leaf for photosynthesis. a) Bundle sheaths are layers of cells surrounding vascular tissue that help regulate the entrance and exit of materials into and out of the leaf vein. C. The general organization of plants helps them maintain homeostasis. 1. The anatomy of plants allows photosynthesis to occur. 2. The products of photosynthesis allow a plant to produce the building blocks needed to maintain its existence. 3. The epidermis in nonwoody plants and cork in woody plants protect the interior of the plant from harm. D . Mechanisms of homeostasis in plants 1. Closure of stomata a) A plant has two ways of preventing water loss at the leaves: the cuticle and the stomata. 2. Phloem transport a) Phloem transports photosynthetic products from the source to the sink. 3. Plant hormones a) Plants rely exclusively on hormones, highly specific chemical signals between plant parts and cells, to respond to stimuli. b) A tropism is a growth response toward or away from a particular stimulus. 4. Mutualistic relationships a) In a mutualistic relationship, both organisms benefit. b) The roots of plants have a mutualistic relationship with fungi 5. Defense mechanisms a) The plant is covered by a thick, impervious cuticle and contains epidermal projections. b) Plants also produce chemical toxins.